12.1- GLYCOLYSIS Flashcards
What are the two types of cellular respiration?
aerobic respiration
anaerobic respiration
What is aerobic respiration and what does it produce?
requires oxygen + produces CO2, water and much ATP
What conditions does anaerobic respiration occur in, and what is produced?
takes place in absence of oxygen + produces lactate (in animals) or ethanol + CO2 (in plants + fungi) but only little ATP in both cases
What four stages can aerobic respiration be divided into?
- glycolysis
- link reaction
- Krebs cycle
- oxidative phosphorylation
What is glycolysis?
splitting of 6-carbon glucose molecule into two 3-carbon pyruvate molecules
What is the link reaction?
3-carbon pyruvate molecules enter into series of reactions which lead to formation of acetylcoenzyme A, a 2-carbon molecule
What is the Krebs cycle?
introduction of acetylcoenzyme A into cycle of oxidation-reduction reactions that yield some ATP + a large quantity of reduced NAD + FAD
What is oxidative phosphorylation?
use of electrons, associated with reduced NAD + FAD, released from Krebs cycle to synthesise ATP with water produced as by-product
What is the initial stage of aerobic + anaerobic respiration?
glycolysis
Where does glycolysis occur?
in cytoplasm of all living cells
What stages can glycolysis be broken down into? (4)
phosphorylation of glucose to glucose pyruvate
splitting of phosphorylated glucose
oxidation of triose phosphate
production of ATP
Glycolysis- phosphorylation of glucose to glucose phosphate #1
glucose must first be made more reactive by addition of two phosphate molecules
Glycolysis- phosphorylation of glucose to glucose phosphate
where do the phosphate molecules come from #2
hydrolysis of two ATP molecules to ADP
this provides energy to activate glucose + lowers activation energy for enzyme-controlled reactions that follow
Glycolysis- splitting of phosphorylated glucose
each glucose molecule split into two 3-carbon molecules known as triose phosphate
Glycolysis- oxidation of triose phosphate
hydrogen removed from each of two triose phosphate molecules + transferred to hydrogen-carrier molecules known as NAD to form reduced NAD
Glycolysis- production of ATP
enzyme-controlled reactions convert each triose phosphate into another 3-carbon molecules called pyruvate
in this process, two molecules of ATP regenerated from ADP
What is the overall yield from one glucose molecules undergoing glycolysis? (3)
two molecules of ATP (4 produced but two used up in initial phosphorylation of glucose + so net increase in two molecules)
two molecules of reduced NAD (have potential to drive energy to produce more ATP)
two molecules of pyruvate
How does glycolysis provide indirect evidence for evolution?
universal feature of every living organism
Where are the enzymes for the glycolytic pathway found?
in cytoplasm of cells + so glycolysis doesn’t require any organelle or membrane for it to happen
In the absence of oxygen, what can happen to the pyruvate produced from glycolysis?
can be converted into either lactate or ethanol during anaerobic respiration
Why is it necessary that the pyruvate produced from glycolysis can be converted into either lactate or ethanol during anaerobic respiration?
necessary to re-oxidised NAD so glycolysis can continue
What is different about the potential energy stored in pyruvate molecules from anaerobic respiration?
yields only small fraction of potential energy stored in pyruvate molecule
What do most organisms do to release the remainder energy from the pyruvate molecules from anaerobic respiration?
most organisms use oxygen to break down pyruvate further
